Process for reducing the amount of carbon in cast-iron or articles cast from iron.



UNITED sTAT ES PATENT OFFICE.

WALTEE 33321:, 01 VIENNA, UBTBIL-HUHGABY. I

PBQCESS FOR. REDUCING THE AMOUNT OF CLEBON IN CAST-IRON OB ARTICLES CAST To all whom it may concern:

Be it known that I, \Vnrrnn Btinen, en- $188!, a subject of the King of Prussia, rmau Emperor, and a resident of Vienna, 6 Austrin-Hungargghave invented remain new and useful Improvements in a Process for Reducing the Amount of Carbon in Cast- Iror. '2? in Articles Cast from Imn, of which the {ollowingis a full, clear, and exact speci- 10 fimlon, 1 ll This invention relates to a process for reducing the amount of carbon in east-iron or in urhciee cast from iron.

The manufacture of steel and other nullties of iron poor in carbon can be e eel/ed by various processes and, in the largest extent, in today effected by the Bessemer procass in which the amount of carbon in the iron is diminished by blowing air through the molten iron, ivhereby a port of the cairhon 08 yell as impuritiesare eliminated by oxidation;

.The qualities of iron so obtained are not used for making castings. For this pur- 26 pose, the Siemens-Mnrtin process is used,

rticularly for large castings of steel.

ll castings, such as carriage fittings, roilwny-car fittings and the like, are usually produced from ordinary cast-iron by the 30 malleableizing pru'ess inasmuch as much carbon as may be is eliminated from the cast-iron by malleableizing the same. This however, is not only very ex ensive, but it also 1'04 uires :1 period of at east 86 eight days for finishing such malleableized castings, and this from the very beginning limits the use of such mulleableized castings to small quantities.

j The present process is to be cimsidered as 401 substitute for the malleableizing process hitherto used and permits the amount of carbon in crude iron to be reduced inthe shortest possible time, to any desired limit.

It is possible by this process to get iron of 4 kilograms resistance and 8%" tensile strength, and the carbon in this is present in the form of pearlite.

This process can be carried out in a cnpols 'furnace, no the elimination of the excess 66 carbon is effected by the aid of sodium h .roxid. The method is as followsz-Fi g -'the requisite quantity of crude iron is melted FBOIZ IRON.

emission-or 1mm 1mm. mums Sept. 28, i one. Application mu :m 4, 1m; mm to. cum.

in a furnace and, in a retort udjoiuiug it and consisting of firebrick or steel or iron. the requisite quantity of sodium hydmxid is melted. The szxlium hydroxid melts at. 750 oentigrade. lVlieu both mosses :u'c sufliciently fluid, they are permitted to flow out through suitable gates into an outer hearth common to both. The quantiti s of iron and sodium hydroxid which enter into reaction with one another are determiuml by the dimensions of the gates. \Vhcu ihecrm'c iron'rich in carbon, containing almut 3.5% of carbon, meets the molten sodimn hydroxid, double decomposition lakes plan-e. in the course of which the sodium hydrwiid transformed into urbouaieof sodium, thereby withdrawing the carbon from the iron. In this reaction hydrogen is liberated and is burned. The high degree of heat so generated transforms the carbon still remaining in the iron into pearlite.

The new process is of advantage in that by the simplest means a soft iron is produced containing any desired amount of carbon which is eminently fit for casting and will make castings which will not show any cracks. The sodium hydroxid acts upon the carbon present in the iron in the form of graphite, forming soft iron and sodium m not only to crude iron before casting cnstings therefrom, but is also suitable for cflec b ing the deearburizntion after the castings are made, which has the additional advanteg'e that the oestin 5 do not require to be an nealed afterward the purpose of away with internal stresses as is absolutely necessary with castings made from caststeel. Moreover, if desired, the finished castings may be entirely decarinrrized.

To carry out the present process with castings having, for example, an average proportion of carbon of 8.5%. they are put into a retort or n mu'llle maximising-sodium i1 droxid or the hydroxid of some other Riki}- line metal, sny,-potaesium hydrcx d, in such prvsbnro of aboul two atmospheres.

quantity tlmt l'l1e castings are cor pletely covered by he molfcn hydroxid. The Lem pvrature of the-retort or nuifile is lhm raised to 1100- 1I50cientigrado and. at lhis Lumpe-ralurc. 'luuarhurization proceeds wry rapidly. Thu retort or inufile is ,rovi h-rl with a safuty valve capable, of withstainling a if the gas pressure in the retort exceeds that. amount, the. valve opens and the passes through a cooling roll into a receptacle filled with a solution of annnonia. wherrhy the sodium lihvrauj-d in the processis dissolved. Tho gase; not absorbed by the ammonia are carried back to the furnace and serve to heat the same. It. i important to ohtain a pressure of about two atmospheres, as this promotes the react-ion. If, for example. the decarburization is to berarried ourto the exi'unlof reducing 3.5% to about 1.5% then. at the tmnporatures givon, heating for about two hours is required. Al the pad of this time, a valve n'midud on the retort or mulllu is opened and the excess of sodium hydroxid is run oil. Then tlw r lortis permitted to (-001 graduall and the caAiugs are l'vnuwod. For the complet docarhurizalion oloastings up lo about :10 millimeters Lhi-Jknc.- about. v-i1 h urs is rcquirvd. lrou doc-arlun'izr-d. by the HbUVO method has a crystalline lifitrous fracture like ingot-iron cast from IHflilih'rs. Hy vha'u; rin the (inn: and temperaim'cs umrloyud, (h'carhiH'iI filion may he so regulated that hr finished prodnnl after annoaling is (-qual 10 line casting in im-1 of cormquondin; quality.

Comparml wilh known nmliuahlcizing proves- 15: and olln-r provvsses of dm-arhurination. the following zulvantagcr; are oh i lainml by the avscnl. prom-( 5:-

(ll Castings of [ho most complicated and doliratv shapes (an hg (fast free from flaw whir-h. as is lcnownJotl'orano difficulty with oiisl-iroin-n'hilo muting from crm-ihlcs in (-asbsn-vl or oruc hlwrluzl from Siemens- .Martin furnarrs ind the like can only be madu. comparatively speaking, in simple forum on account oi the and flaws which occur (hi-ruin. Tho quality is neverlheless the amo as with sir-0i castings.

(:2) In order to rcdnra lhu amount of rarhon in a rasling from 3.5) x-arhon to fine stool with 0.5 rarhon only. allogflhvr ahonl. ton hours are. required. Tho PI'UHSHUSllllllerto uswl in malh-alvlrixin require at least svven da (3) No altvrario'n of''hapoin the castings takes place a.- is the raw in nzall alih-izing prorrsms, in whivh lhv raslings have to be closely packed in oxidizing reagents, as in the prusontprms the (flHlHgh (22H) freely expand in all dirrulions. 'l hi avoids the uevcssity for again boating the castings To red-heat and adjmting. By iheproFa-ni prorus.., for inst-alive, moior. cylinders will: very thin rim: (an hrprmlucrd win-iv, haw-(inform all and they alterations in Sllfijli occurring in tho malh-ahim ing proress could no! hr ma l? good.

(4) The pl hz-L lli ducarhurizing prom-s5 aim cheapo! lhar any other known prong. as, on account of its rapidity. ii only requires a small quantity of fuel and also dons not require lar'w and (:(unplirrm-l iuslallaiior'zs. The cost oi the sodium hyn .xid employed fully div-"Hal by The sod um and sodium carbonate that are iwzm'nrcd.

The prove lain- 1 placc'in the following way:'lVh0u tho'cast-iron is immersed in the sodium hydroxid at red hunt, the carbon at the Miriam of the iron enters into oomhination'witlz he sod um hydroxid forming sodium carbonate. hydrogen becoming free. As soon as tin-ire is a suprrlicial docarlnrrizalion, which takes place at about 7.10". the process alum t. unlircl stops until the temperatnrc is r; sod to 1050.10 1100". At this moment. tho iron which is still rirh in carhon. namvlv that under the pun! superficial layer of ironm-aanvncos to softvn and carhon lravols outv-mrd and ('omhiiws, not with the carhonifirom iron, but with the sodium hydroxid. Thus. the pru-:e'. s mntinuc-s and thr onn-r iawr of pure iron. whirh is of incrrasing l no 1 whose nix-hing point is ahouL 4H0 higln-r than that of the rarhonih -ous iron, prowrfs thc rusting againstuurlting and uonsmgnuntlyagainst alteration of l1apu. If. for instanrv, a round rod alum! ill) miliimetrrs lhirl-Z is taken out after tw hour;-. and lu'okvu. ii' will how on llauiitaizlu fen! about i millimutvrs thick, a clean rrys'tallino iron fraclurv and then toward Hi0- orn the rivhnvss in cal-hon increases. lf, howow-r, thv rod is gradually cooled from Him); llH carbon is again completely and uvvnly distributed own all parts.

lt may lw rmnarlced that vast-iron with combined varimn is easier to dwarlnn'ize than iron that qontains graphite.

In the al'orvsaid manner, largo castings, snrh as cylinders and machinery frames. may ho so far ih-varimrizcd as to have on the out.- side a thirk rough layr-r of iron of solar-,3 h) 3 millimmvr: thickness. This yields the soil (\lllifll advantage hat the pier-vs will he rapahlu Jl' min-h grwalor rvsislanco lo frarlurv and will afford a much hvtu-r holding surfaci for srrizws, nuts and fixings than is the vase with hard (7:155 iron.

l-la 'ing now particularly drscrihcd and awvrtainod the nature of my'said invontion and in what mania-r tho same is io he purformed, I declare laal wha'l 1 claim i'-.'---

1. The P'lncQS-S for diniiniahing th unount. of ca'rh'on in rust-iron, whii'rh r-u Its in treating the met-iron at a touqx'raum: from him) to 1150 aivgl'w. with molten oadiiim Ill) bydro xid, whereby the hydroxid acts by he carbon.

, 2.- The process for dimi of carbon in e treating the ca drcxid at a still in her tempe the hydroxid a cast-iron, which consists in st-iron at a tem erature from degrees C. wit sodium h rature,wber y cts' y diffusxon on the carbon. 1

"in witnea whereof I hnye hemu'nte signed I by'name this 23rd day qf May 1908, in the a mshmg the amount presence of two subscnbmg WIWS- WALTER RUBEL A. FUHRON MAL/124v, 

